The results of investigations of spent moulding sands taken from the mould in which the metal core cooling system - to increase the
cooling rate of the ladle casting - was applied, are presented in the hereby paper. The changes of the spent moulding sand at the casting
external side being the result of degradation and destruction processes of organic binder, were analysed in this publication. Since the
reclaimed material, obtained as a result of the mechanical reclamation of spent sands of the same type, is used as a grain matrix of the
moulding sand, the amount of a binder left from the previous technological cycle is essential for the sound castings production. On the
bases of investigations of the thermal analysis, ignition losses, dusts contents and pH values of the samples taken from the spent sand the
conditions under which the process of gases displacing in the casting mould was realised as well as factors limiting the efficient mould
degassing - were considered in this study. The possible reason of a periodical occurrence of an increased number of casting defects due to
changing gas volume emission, being the reason of the realised technological process, was indicated.
The results of investigations of the granulation process of foundry dusts generated in the dry mechanical reclamation process of used sands, where furan resins were binders are presented in the paper. Investigations concerned producing of granules of the determined dimensions and strength parameters. Granules were formed from the dusts mixture consisting in 50 mass% of dusts obtained after the reclamation of the furane sands and in 50 mass % of dusts from sands with bentonite. Dusts from the bentonite sands with water were used as a binder allowing the granulation of after reclamation dusts from the furane sands. The following parameters of the ready final product were determined: moisture content (W), shatter test of granules (Wz) performed directly after the granulation process and after 1, 3, 5, 10 days and nights of seasoning, water-resistance of granules after 24 hours of being immersed in water, surface porosity ep and volumetric porosity ev. In addition the shatter test and water-resistance of granulate dried at a temperature of 105oC were determined. Investigations were performed at the bowl angle of inclination 45o, for three rotational speeds of the bowl being: 10, 15, 20 rpm. For the speed of 10 rpm the granulation tests of dusts mixture after the preliminary mixing in the roller mixer and with the addition of water-glass in the amount of 2% in relation to the amount of dust were carried out. The obtained results indicate that the granulator allows to obtain granules from dusts originated from the reclamations of moulding sands with the furane resin with an addition of dusts from the bentonite sands processing plants.
In the paper presented are results of a research on influence of electrical and physico-chemical properties of materials being parts of
multicomponent and multimaterial systems used in foundry practice on efficiency and effectiveness of microwave heating. Effectiveness
of the process was evaluated on the grounds of analysis of interaction between selected parameters of permittivity and loss factor, as well
as collective index of energy absorbed, reflected and transmitted by these materials. In the examinations used was a stand of waveguide
resonance cavity for determining electrical properties and a stand of microwave slot line for determining balance of microwave power
emitted into selected materials. The examinations have brought closer the possibility of forecasting the behaviour of multimaterial systems
like e.g. model, moulding sand or moulding box in microwave field on the grounds of various electrical and physico-chemical properties.
On the grounds of analysis of the results, possible was selecting a group of materials designed for building foundry instrumentation to be
effectively used in electromagnetic field.
The results of investigations of moulding sands with an inorganic binder called GEOPOL, developed by the SAND TEAM Company are
presented in the paper. Hardeners of various hardening rates are used for moulding sands with this binder. The main aim of investigations
was determination of the influence of the hardening rate of moulding sands with the GEOPOL binder on technological properties of these
sands (bending strength, tensile strength, permeability and grindability). In addition, the final strength of moulding sands of the selected
compositions was determined by two methods: by splitting strength and shear strength measurements. No essential influence of the
hardening rate on such parameters as: permeability, grindability and final strength was found. However, the sand in which the slowest
hardener (SA 72) were used, after 1 hour of holding, had the tensile and bending strength practically zero. Thus, the time needed for taking
to pieces the mould made of such moulding sand will be 1.5 - 2 hours.
No-bake process refers to the use of chemical binders to bond the moulding sand. Sand is moved to the mould fill station in preparation for
filling of the mould. A mixer is used to blend the sand with the chemical binder and activator. As the sand exits the mixer, the binder
begins the chemical process of hardening. This paper presents the results of decomposition of the moulding sands with modified ureafurfuryl
resin (with the low content of furfuryl alcohol below 25 % and different activators: organic and inorganic) on a quartz matrix,
under semi-industrial conditions. Investigations of the gases emission in the test foundry plant were executed according to the method
extended in the Faculty of Foundry Engineering (AGH University of Science and Technology). Article presents the results of the emitted
chosen aromatic hydrocarbons and loss on ignition compared with the different activators used to harden this resin. On the bases of the
data, it is possible to determine the content of the emitted dangerous substances from the moulding sand according to the content of loss on
ignition.
A thermo-insulating moulding sand with a binder made of aluminosilicate microspheres with organic binder was subjected to testing. The aim of the analysis was to determine selected technological properties of the developed compounds. Compressive strength, friability and gas permeability were determined. The binder content was changed within a range of 5÷20 wt% with a 5% step. The applied matrix is characterized by good thermo-insulating properties and a small size of grains, while synthetic organic binder has favourable functional properties, among which the most noteworthy are the extended life and setting time, good rheological properties as well as high resistance to chemical agents. The intended use of the compound is the casting of 3D CRS (Composite Reinforced Skeletons), which are characterized by a well-developed heat transfer surface area, good absorption of impact energy, low mass and a target thickness of connectors within a range of 1.5÷3 mm. The construction of 3D CRS castings is an original concept developed by the employees of the Department of Foundry Engineering at the Silesian University of Technology.
The paper presents the results of an investigation of the gases emission of moulding sands with an inorganic (geopolymer) binder with a relaxation additive, whose main task is to reduce the final (residual) strength and improves knocking-out properties of moulding sand. The moulding sand without a relaxation additive was the reference point. The research was carried out using in accordance with the procedure developed at the Faculty of Foundry Engineering of AGH - University of Science and Technology, on the patented stand for determining gas emissions. Quantification of BTEX compounds was performed involving gas chromatography method (GC).The study showed that the introduction of relaxation additive has no negative impact on gas emissions - both in terms of the total amount of gases generated, as well as emissions of BTEX compounds. Among the BTEX compounds, only benzene is emitted from the tested moulding sands. Its emission is associated with the introduction a small amount of an organic hardener from the group of esters.
The analysis of after reclamation dusts generated during the reclamation treatment of test portions of two kinds of polydispersive material in the Regmas device, is presented in the hereby paper. For the comparative purpose the fresh moulding sand marked as quartz sand „Sibelco” –1K 0.40/0.32/0.20, J88, >14000C, WK = 1.20 (acc. PN-83/H-11077), as well as the spent moulding sand, which was previously subjected to the primary reclamation and to dedusting, were used. Conditions of the process treatment were forced by the frequency of supplying the vibratory drive motors being successively 40, 50 and 60Hz for 5, 10 and 15 min. and by causing a diversified material flow through the functional system of the device (charging hopper, abrasive chamber acting as a buffer space). Two states of the process treatment, when a material was flowing through the chamber, were applied. In the first one, an intergranular surface abrasion of grains occurred as a result of the granular material circulation in the chamber forced by the vibratory drive. In the second one, the forced material flow was performed in the presence of crushing elements (steel balls), additionally introduced into the abrasive chamber. Analyses of the device influence were performed by determinations of the amount of dusts separated in the pneumatic classifier and analysis of their grain sizes by means of Analysette 22NanoTec.
Bentonites and clays are included in the group of drilling fluids materials. The raw materials are mainly clay minerals, which are divided into several groups, like montmorillonite, kaolinite, illite, biotite, muscovite, nontronite, anorthoclase, microcline, sanidine or rutile, differing in chemical composition and crystal lattice structure. Clay minerals have a layered structure forming sheet units. The layers merge into sheets that build up to form the structure of the mineral.
The aim of the studies carried out in the ŁUKASIEWICZ Research Network - Foundry Research Institute is to explore the possibility of using minerals coming from Polish deposits.
The article outlines the basic properties of hybrid bentonites, which are a mixture of bentonite clay called beidellite, originating from overburden deposits of the Turoszów Mine, and foundry bentonite from one of the Slovak deposits. As part of the physico-chemical tests of minerals, measurements included in the PN-85/H-11003 standard, i.e. montmorillonite content, water content and swelling index, were carried out. Additionally, the loss on ignition and pH chemical reaction were determined. Based on the thermal analysis of raw materials, carried out in the temperature range from 0 to 1000oC, changes occurring in these materials during heating, i.e. thermal stability in contact with liquid metal, were determined.
Examinations of the sand mixture based on pure clay and bentonite and of the sand mixture based on hybrid bentonites enabled tracing changes in permeability, compressive strength and tensile strength in the transformation zone as well as compactability referred to the clay content in sand mixture. Selected technological and strength parameters of synthetic sands are crucial for the foundry, because they significantly affect the quality of the finished casting.
Based on the analysis of the results, the optimal composition of hybrid bentonite was selected.
In this work, the influence of microwave drying parameters such as irradiation time and microwave power level on the properties of synthetic moulding sands is presented. Determination of compressive strength Rc s, shear strength Rt s and permeability Ps of synthetic moulding sands with the addition of two different bentonites, after drying process with variable microwave parameters were made. The research works were carried out using the microwave oven with regulated power range of the electromagnetic field. From the results obtained, the significant influence of both drying time and microwave power level on the selected properties of moulding sands was observed. In comparison to the conventional drying method, microwave drying allows to obtain higher compressive strength of the synthetic moulding sand. The influence of application microwave irradiation on permeability was not observed. Higher strength characteristics and shorter drying time are major advantages of application of the electromagnetic irradiation for drying of the synthetic moulding sand with regard to conventional drying method.
The results of researches of sorption processes of surface layers of components of sand moulds covered by protective coatings are
presented in the hereby paper. Investigations comprised various types of sand grains of moulding sands with furan resin: silica sand,
reclaimed sand and calcined in temperature of 700oC silica sand. Two kinds of alcoholic protective coatings were used – zirconium and
zirconium – graphite. Tests were performed under condition of a constant temperature within the range 30 – 35oC and high relative air
humidity 75 - 80%. To analyze the role of sand grains in sorption processes quantitavie moisture sorption with use of gravimetric method
and ultrasonic method were used in measurements. The tendency to moisture sorption of surface layers of sand moulds according to the
different kinds of sand grains was specified. The effectiveness of protective action of coatings from moisture sorption was analyzed as
well.
Knowledge of the role of sand grains from the viewpoint of capacity for moisture sorption is important due to the surface casting defects
occurrence. In particular, that are defects of a gaseous origin caused by too high moisture content of moulds, especially in surface layers.
The results of investigations of thermal reclamation of spent moulding sands originating from an aluminum alloy foundry plant are
presented in this paper. Spent sands were crushed by using two methods. Mechanical fragmentation of spent sand chunks was realized in
the vibratory reclaimer REGMAS. The crushing process in the mechanical device was performed either with or without additional
crushing-grinding elements. The reclaimed material obtained in this way was subjected to thermal reclamations at two different
temperatures. It was found that a significant binder gathering on grain surfaces favors its spontaneous burning, even in the case when
a temperature lower than required for the efficient thermal reclamation of furan binders is applied in the thermal reclaimer. The burning
process, initiated by gas burners in the reclaimer chamber, generates favorable conditions for self-burning (at a determined amount of
organic binders on grain surfaces). This process is spontaneously sustained and decreases the demand for gas. However, due to the
significant amount of binder, this process is longer than in the case of reclaiming moulding sand prepared with fresh components.
The results of investigations of spent moulding sands taken from the mould at various distances from the surface of the produced casting,
are presented in the paper. The casting mould was made with an application of the cooling system of the metal core in order to increase the
cooling rate of the ladle casting. As temperature measurements in the mould indicated the heat flow from the metal did not create
conditions for the complete burning of a moulding sand. The analysis was performed to find out changes of spent moulding sands caused
by degradation and destruction processes of organic binders. Conditions occurring in the casting mould were discussed on the bases of
testing: ignition losses, dusts contents, pH reactions and the surface morphology of the moulding sand samples. Factors limiting the
effective mould degassing were pointed out. Operations, possible for realization, which can limit the reasons of a periodical occurrence of
increased amounts of casting defects due to changing gas evolution rates being the result of the technological process, were also indicated.
Growing emission requirements are forcing the foundry industry to seek new, more environmentally friendly solutions. One of the
solutions may be the technologies of preparing moulding and core sands using organic biodegradable materials
as binders. However, not only environmental requirements grow but also those related to the technological properties
of moulding sand. Advancing automation and mechanization of the foundry industry brings new challenges related to the moulding sands.
Low elasticity may cause defects during assembly of cores or moulds by the manipulators.
The paper presents the study of flexibility in the room temperature according to new method and resistance to thermal deformation of selfhardening
moulding sands with furfuryl resin, containing biodegradable material PCL. The task of the new additive is to reduce the
moulding sands harmfulness to the environment and increase its flexibility in the room temperature. The impact of the additive and the
effect of the amount of binder on the properties of mentioned moulding sands were analysed. Studies have shown that the use of 5% of
PCL does not change the nature of the thermal deformation curve, improves the bending strength of tested moulding mixtures and
increases their flexibility at room temperature.